par-term-render 0.7.2

//! Pipeline and bind group creation for custom shader renderer.
//!
//! This module contains helpers for creating wgpu bind groups, bind group layouts,
//! and render pipelines for custom shaders.

use wgpu::*;

use super::cubemap::CubemapTexture;
use super::textures::ChannelTexture;

/// Create the bind group layout for custom shaders with all 14 entries.
///
/// Layout:
/// - 0: Uniform buffer
/// - 1: iChannel0 texture (user texture, Shadertoy compatible)
/// - 2: iChannel0 sampler
/// - 3: iChannel1 texture (user texture)
/// - 4: iChannel1 sampler
/// - 5: iChannel2 texture (user texture)
/// - 6: iChannel2 sampler
/// - 7: iChannel3 texture (user texture)
/// - 8: iChannel3 sampler
/// - 9: iChannel4 texture (terminal content)
/// - 10: iChannel4 sampler
/// - 11: iCubemap texture (cubemap for environment mapping)
/// - 12: iCubemap sampler
/// - 13: Custom shader controls uniform buffer
pub fn create_bind_group_layout(device: &Device) -> BindGroupLayout {
    device.create_bind_group_layout(&BindGroupLayoutDescriptor {
        label: Some("Custom Shader Bind Group Layout"),
        entries: &[
            // Uniform buffer (binding 0)
            BindGroupLayoutEntry {
                binding: 0,
                visibility: ShaderStages::VERTEX | ShaderStages::FRAGMENT,
                ty: BindingType::Buffer {
                    ty: BufferBindingType::Uniform,
                    has_dynamic_offset: false,
                    min_binding_size: None,
                },
                count: None,
            },
            // iChannel0 texture (binding 1) - user texture, Shadertoy compatible
            BindGroupLayoutEntry {
                binding: 1,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Texture {
                    sample_type: TextureSampleType::Float { filterable: true },
                    view_dimension: TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // iChannel0 sampler (binding 2)
            BindGroupLayoutEntry {
                binding: 2,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Sampler(SamplerBindingType::Filtering),
                count: None,
            },
            // iChannel1 texture (binding 3) - user texture
            BindGroupLayoutEntry {
                binding: 3,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Texture {
                    sample_type: TextureSampleType::Float { filterable: true },
                    view_dimension: TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // iChannel1 sampler (binding 4)
            BindGroupLayoutEntry {
                binding: 4,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Sampler(SamplerBindingType::Filtering),
                count: None,
            },
            // iChannel2 texture (binding 5) - user texture
            BindGroupLayoutEntry {
                binding: 5,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Texture {
                    sample_type: TextureSampleType::Float { filterable: true },
                    view_dimension: TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // iChannel2 sampler (binding 6)
            BindGroupLayoutEntry {
                binding: 6,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Sampler(SamplerBindingType::Filtering),
                count: None,
            },
            // iChannel3 texture (binding 7) - user texture
            BindGroupLayoutEntry {
                binding: 7,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Texture {
                    sample_type: TextureSampleType::Float { filterable: true },
                    view_dimension: TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // iChannel3 sampler (binding 8)
            BindGroupLayoutEntry {
                binding: 8,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Sampler(SamplerBindingType::Filtering),
                count: None,
            },
            // iChannel4 texture (binding 9) - terminal content
            BindGroupLayoutEntry {
                binding: 9,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Texture {
                    sample_type: TextureSampleType::Float { filterable: true },
                    view_dimension: TextureViewDimension::D2,
                    multisampled: false,
                },
                count: None,
            },
            // iChannel4 sampler (binding 10)
            BindGroupLayoutEntry {
                binding: 10,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Sampler(SamplerBindingType::Filtering),
                count: None,
            },
            // iCubemap texture (binding 11) - cubemap for environment mapping
            BindGroupLayoutEntry {
                binding: 11,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Texture {
                    sample_type: TextureSampleType::Float { filterable: true },
                    view_dimension: TextureViewDimension::Cube,
                    multisampled: false,
                },
                count: None,
            },
            // iCubemap sampler (binding 12)
            BindGroupLayoutEntry {
                binding: 12,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Sampler(SamplerBindingType::Filtering),
                count: None,
            },
            // Custom shader controls uniform buffer (binding 13)
            BindGroupLayoutEntry {
                binding: 13,
                visibility: ShaderStages::FRAGMENT,
                ty: BindingType::Buffer {
                    ty: BufferBindingType::Uniform,
                    has_dynamic_offset: false,
                    min_binding_size: None,
                },
                count: None,
            },
        ],
    })
}

/// Inputs used to create a custom shader bind group.
pub struct BindGroupInputs<'a> {
    /// The bind group layout.
    pub layout: &'a BindGroupLayout,
    /// Uniform buffer for shader parameters.
    pub uniform_buffer: &'a Buffer,
    /// Terminal content texture view (iChannel4).
    pub intermediate_texture_view: &'a TextureView,
    /// Uniform buffer for custom shader controls.
    pub custom_uniform_buffer: &'a Buffer,
    /// Sampler for the intermediate texture.
    pub sampler: &'a Sampler,
    /// Array of 4 channel textures (iChannel0-3, Shadertoy compatible).
    pub channel_textures: &'a [ChannelTexture; 4],
    /// Cubemap texture for environment mapping (iCubemap).
    pub cubemap: &'a CubemapTexture,
}

/// Create a bind group for the custom shader with all textures and uniforms.
pub fn create_bind_group(device: &Device, inputs: BindGroupInputs<'_>) -> BindGroup {
    let BindGroupInputs {
        layout,
        uniform_buffer,
        intermediate_texture_view,
        custom_uniform_buffer,
        sampler,
        channel_textures,
        cubemap,
    } = inputs;

    device.create_bind_group(&BindGroupDescriptor {
        label: Some("Custom Shader Bind Group"),
        layout,
        entries: &[
            BindGroupEntry {
                binding: 0,
                resource: uniform_buffer.as_entire_binding(),
            },
            // iChannel0 (user texture, Shadertoy compatible)
            BindGroupEntry {
                binding: 1,
                resource: BindingResource::TextureView(&channel_textures[0].view),
            },
            BindGroupEntry {
                binding: 2,
                resource: BindingResource::Sampler(&channel_textures[0].sampler),
            },
            // iChannel1 (user texture)
            BindGroupEntry {
                binding: 3,
                resource: BindingResource::TextureView(&channel_textures[1].view),
            },
            BindGroupEntry {
                binding: 4,
                resource: BindingResource::Sampler(&channel_textures[1].sampler),
            },
            // iChannel2 (user texture)
            BindGroupEntry {
                binding: 5,
                resource: BindingResource::TextureView(&channel_textures[2].view),
            },
            BindGroupEntry {
                binding: 6,
                resource: BindingResource::Sampler(&channel_textures[2].sampler),
            },
            // iChannel3 (user texture)
            BindGroupEntry {
                binding: 7,
                resource: BindingResource::TextureView(&channel_textures[3].view),
            },
            BindGroupEntry {
                binding: 8,
                resource: BindingResource::Sampler(&channel_textures[3].sampler),
            },
            // iChannel4 (terminal content)
            BindGroupEntry {
                binding: 9,
                resource: BindingResource::TextureView(intermediate_texture_view),
            },
            BindGroupEntry {
                binding: 10,
                resource: BindingResource::Sampler(sampler),
            },
            // iCubemap (cubemap for environment mapping)
            BindGroupEntry {
                binding: 11,
                resource: BindingResource::TextureView(&cubemap.view),
            },
            BindGroupEntry {
                binding: 12,
                resource: BindingResource::Sampler(&cubemap.sampler),
            },
            // Custom shader controls
            BindGroupEntry {
                binding: 13,
                resource: custom_uniform_buffer.as_entire_binding(),
            },
        ],
    })
}

/// Create the render pipeline for custom shaders.
///
/// # Arguments
/// * `device` - The wgpu device
/// * `shader_module` - Compiled shader module
/// * `bind_group_layout` - Bind group layout for the pipeline
/// * `surface_format` - Target surface texture format
/// * `label` - Optional label for the pipeline
pub fn create_render_pipeline(
    device: &Device,
    shader_module: &ShaderModule,
    bind_group_layout: &BindGroupLayout,
    surface_format: TextureFormat,
    label: Option<&str>,
) -> RenderPipeline {
    let pipeline_layout = device.create_pipeline_layout(&PipelineLayoutDescriptor {
        label: Some(label.unwrap_or("Custom Shader Pipeline Layout")),
        bind_group_layouts: &[Some(bind_group_layout)],
        immediate_size: 0,
    });

    device.create_render_pipeline(&RenderPipelineDescriptor {
        label: Some(label.unwrap_or("Custom Shader Pipeline")),
        layout: Some(&pipeline_layout),
        vertex: VertexState {
            module: shader_module,
            entry_point: Some("vs_main"),
            buffers: &[],
            compilation_options: Default::default(),
        },
        fragment: Some(FragmentState {
            module: shader_module,
            entry_point: Some("fs_main"),
            targets: &[Some(ColorTargetState {
                format: surface_format,
                // Use premultiplied alpha blending since shader outputs premultiplied colors
                blend: Some(BlendState::PREMULTIPLIED_ALPHA_BLENDING),
                write_mask: ColorWrites::ALL,
            })],
            compilation_options: Default::default(),
        }),
        primitive: PrimitiveState {
            topology: PrimitiveTopology::TriangleStrip,
            ..Default::default()
        },
        depth_stencil: None,
        multisample: MultisampleState::default(),
        cache: None,
        multiview_mask: None,
    })
}